冲绳海槽至马里亚纳海沟重力异常和地壳结构的初步研究

根据我们实测的水深、重力连续剖面资料,计算了自东海至北斐济盆地的地壳厚度。本文旨在对冲绳海槽至马里亚纳海沟的重力异常和地壳结构进行初步的研究。该地段位于太平洋板块俯冲带以西,构造活动十分复杂、剧烈,并含有多种类型的地壳结构。     

云贵高原晚新生代孢粉植物群与环境变迁

本文依据２０多个剖面（钻孔）近７００个样品的孢粉资料及古地磁极性年表建立了云贵高原４Ｍａ以来的孢粉时间序列，并划分了四个区域孢粉组合带，１７个孢粉组合亚带。依据孢粉混杂堆积的出现，认为云贵高原的上升始于２．８ＭａＢ．Ｐ．，加剧于０．８ＭａＢ．Ｐ．前后。前期地形相对高度＜１０００ｍ，后期相对高度达１５００ｍ；地貌经历了开阔盆地－低洼盆地－山地湖盆－高山湖盆的演化。气候经历了古季风、现代季风的发展过程     

On the estimation of mooring line characteristic resistance for reliability analysis

The main aim of this work is to derive a correct formulation for the characteristic resistance of a mooring line segment with lognormally distributed component resistances and substitute an equation proposed by Vazquez-Hernandez et al. [Vazquez-Hernandez AO, Ellwanger GB, Sagrilo LVS. Reliability-based comparative study for mooring lines design criteria. Appl Ocean Res 2006; 28(6):398–406] in a paper published in this journal, which is not correct. The mooring line is considered as a series system and the resistances of individual components of a line segment are statistically independent and identically distributed; furthermore, the case of normally distributed component resistances is also discussed. A comparison with the corresponding equation proposed by DNV-OS-E301 is given. Results show that the formula proposed by Vazquez-Hernandez et al. [Vazquez-Hernandez AO, Ellwanger GB, Sagrilo LVS. Reliability-based comparative study for mooring lines design criteria. Appl Ocean Res 2006; 28(6):398–406] overestimates quite significantly the characteristic resistance of a mooring line segment.     

Fully nonlinear numerical wave tank (NWT) simulations and wave run-up prediction around 3-D structures

A finite-difference scheme and a modified marker-and-cell (MAC) algorithm have been developed to investigate the interactions of fully nonlinear waves with two- or three-dimensional structures of arbitrary shape. The Navier–Stokes (NS) and continuity equations are solved in the computational domain and the boundary values are updated at each time step by the finite-difference time-marching scheme in the framework of a rectangular coordinate system. The fully nonlinear kinematic free-surface condition is implemented by the marker-density function (MDF) technique developed for two fluid layers.To demonstrate the capability and accuracy of the present method, the numerical simulation of backstep flows with free-surface, and the numerical tests of the MDF technique with limit functions are conducted. The 3D program was then applied to nonlinear wave interactions with conical gravity platforms of circular and octagonal cross-sections. The numerical prediction of maximum wave run-up on arctic structures is compared with the prediction of the Shore Protection Manual (SPM) method and those of linear and second-order diffraction analyses based on potential theory and boundary element method (BEM). Through this comparison, the effects of non-linearity and viscosity on wave loading and run-up are discussed.     

Seismic analyses of Cenozoic contourite drift development in the Northern Norwegian Sea

Four drift accumulations have been identified on the continental margin of northern Norway; the Lofoten Drift, the Vesterålen Drift, the Nyk Drift and the Sklinnadjupet Drift. Based on seismic character these drifts were found to belong to two main groups; (1) mounded, elongated, upslope accretion drifts (Lofoten Drift, Vesterålen Drift and Nyk Drift), and (2) infilling drifts (Sklinnadjupet Drift). The drifts are located on the continental slope. Mainly surface and intermediate water circulation, contrary to many North Atlantic and Antarctic drifts that are related to bottom water circulation, and sediment availability have controlled their growth. Sediments were derived both from winnowing of the shelf and upper slope and from ice sheets when present on the shelf. The main source area was the Vøring margin. This explains the high maximum average sedimentation rate of the nearby Nyk (1.2 m/ka) and Sklinnadjupet (0.5 m/ka) Drifts compared with the distal Lofoten (0.036 m/ka) and Vesterålen (0.060 m/ka) Drifts. The high sedimentation rate of the Nyk Drift, deposited during the period between the late Saalian and the late Weichselian is of the same order of magnitude as previously reported for glacigenic slope sediments deposited during glacial maximum periods only. The Sklinnadjupet Drift is infilling a paleo-slide scar. The development of the infilling drift was possible due to the available accommodation space, a slide scar acting as a sediment trap. Based on the formation of diapirs originating from the Sklinnadjupet Drift sediments we infer these sediments to have a muddy composition with relatively high water content and low density, more easily liquefied and mobilised compared with the glacigenic diamictons.     

中太平洋CP25岩心的矿物、稀土元素及Sr、Nd同位素组成--晚新生代海底火山活动的证据

中太平洋ＣＰ２５岩心沉积物中钙十字沸石、蒙脱石／伊利石比值（Ｍ／Ｉ）、稀土元素含量、铈异常（δＣｅ）、铕异常（δＥｕ）及Ｓｒ、Ｎｄ同位素特征作为海底火山活动的证据,揭示了中太平洋海盆晚新生代以来火山活动和沉积的历史。其结果是,早中新世约２０～１７ＭａＢ．Ｐ．间,火山活动逐渐强烈,在１７ＭａＢ．Ｐ．最强烈,使得沉积物具有高Ｍ／Ｉ和∈Ｎｄ、低δＣｅ和８７Ｓｒ／８６Ｓｒ。１７～１ＭａＢ．Ｐ．发生沉积间断。１ＭａＢ．Ｐ．至现代,火山活动较早中新世减弱     

Harmonic generation past a submerged porous step

Experiments were conducted in a wave flume to study the differences between harmonic evolution of monochromatic waves as they propagate over a submerged impermeable or porous step under non-breaking conditions. Results are used as a preliminary analysis to establish some engineering design criteria on harmonic generation on submerged porous structures. The root-mean-squared wave height evolution is also studied and compared to linear models as a first approximation. It is shown that porous structure increases the effective relative depth and decreases the relative wave height, resulting in a lower Ursell number and a lower chance to generate harmonics. The effective water depth over a step as defined in the paper, provides information to evaluate the potential harmonic generation.     

近海污损生物的调查方法

近海海区污损生物调查有浮标挂板法和海上设施（浮标及其锚碇系统，Ｍａｒｅｘ水文浮标，移动式钻井平台和固定式生产平台）采样法。由于近海海区污损生物调查工作的特殊性和艰难性，笔者提出了利用已有的海上设施，尤其是固定式平台来积累近海污损生物资料，以便进行生态学研究。     

晚新生代亚洲干旱气候发展与全球变冷联系的风尘沉积证据

在干旱气候背景下常常有风尘物质的释放和传输,风尘沉积被认为是干旱环境变化良好的地质记录。在亚洲中部和中国北方,大面积的干旱区被沙漠戈壁覆盖,这些地区是粉尘物质的重要源地,释放的风尘物质影响局地和区域环境,并通过参与生物地球化学循环等影响更大空间尺度的气候变化。因此,亚洲中部干旱气候的形成和演化以及发展趋势一直受到重视。长期以来,关于晚新生代亚洲中部干旱气候发展的驱动机制至少有两种解释:一是青藏高原的隆升控制着亚洲中部的干旱化过程,随着高原的阶段性隆升亚洲干旱气候逐步增强;二是晚新生代全球变冷直接驱动着亚洲变干,全球变冷是主导因素。中国黄土高原及其周边地区堆积的黄土-红粘土序列是指示亚洲干旱化过程良好的地质记录,通过对新获得的风尘堆积记录的分析,发现在晚新生代中国风尘堆积的时空演化与全球变冷有较好的对应,全球变冷可以促使亚洲中部干旱气候发展并加强粉尘活动,而青藏高原隆升的幅度和时间还不清楚,进而认为是全球变冷而不是青藏高原隆升直接驱动亚洲内陆的阶段性变干。基于这些结果,我们认为以前关于青藏高原隆升影响全球气候的结论可能高估了青藏高原在地球环境演化中的作用,关于高原隆升直接驱动亚洲干旱化的结论还需要检验。